Slides from Aarhus.rb meetup on 15/1/2015.

1. It's a Jungle Out There
Matúš Tomlein
PhD Fellow at Aarhus University
@matus_tomlein
Aarhus.rb meetup, 5.1.2015

2. The Internet of Things Is
• A buzzword
• Connecting every-day devices to the Internet
• Washing machines, doors, shoes, ...

3. Charts From Every Talk About IoT

4. The Old Internet
twitter.com spotify.com
Clients
Servers
POST /tweet GET /songs/next

5. The New Internet
twitter.com
Clients
Servers
POST /tweet
FE80::0202:B3FF
:FE1E:8329
GET /fuel POST /activate
AB78::1378:F3B
B:FE1E:8329
GET /status

6. Well, actually...
twitter.com
Clients
Servers
POST /tweet
FE80::0202:B3FF
:FE1E:8329
GET /fuel POST /lamps/12/activate
AB78::1378:F3B
B:FE1E:8329
GET /status

7. What is the development
for the IoT like?

8. We, Web developers, Are Spoiled
• Deploying/updating our apps is easy
• Only have to care about a few of servers in the production
• We can always SSH into a server and see what's wrong
• Our servers run in the comfort of the cloud
• Testing/debugging also easy
• We have all the computing power we want
• We can use any technology we want

9. Meanwhile on Embedded Devices
• Deploying/updating is a nightmare
• There can be dozens/thousands of embedded systems running your app
• Little power, sometimes constrained battery life
• Testing/debugging on the device takes effort
• You have no control of the environment they are in
• The added trouble of communication with and between devices
• Security...
• You are stuck with C, C++, maybe Java (unless you run on Unix)

10. At least the last point
is not true

11. MRuby
• Another interpreter for Ruby
• The other ones won't run without OS or on RTOS
• Also a compiler and VM
• Very lightweight (<128kb)
• Compatible with Ruby 1.9 syntax
• Runs on anything that can run C

12. MRuby is Lightweight
• Only platform independent functionality
• Everything else is a gem (mrbgem)
• e.g. IO, threads, require

13. mrbgems
• Defined in build_config.rb
• Can be:
• Pure Ruby – Defines the extension class in Ruby
• Pure C – Builds the class in C
• C and Ruby – Defines some methods in C and
some in Ruby

14. MRuby is Embeddable
• Can be run inside other applications
• Great for scripting, configuration
*.rb
/usr/bin/ruby
C/C++ app
*.rb
bytecode
libmruby.a
Source: http://www.slideshare.net/yamanekko/rubyconf2013?qid=dd845db4-dda5-44a5-81c3-0fa63ca520f2&v=qf1&b=&from_search=8

15. 4 Ways to Run MRuby
1. Interpreted
2. Interactive shell
3. Bytecode
4. Generating C code
Source: http://blog.mruby.sh/201207020720.html

16. Interpreted
• Just like any other Ruby app
$ mruby hello_world.rb
Hello World
• Good for testing
• Overhead

17. Interactive Shell
• Just like irb
$ mirb
mirb - Embeddable Interactive Ruby Shell
> puts "Hello"
Hello
=> nil

18. Bytecode
$ mrbc hello_world.rb
• Will produce platform independent bytecode in
hello_world.mrb
$ mruby -b hello_world.mrb
Hello World
• Will run the bytecode in a VM
• Less overhead – no parsing
• Still need the mruby program to run it

19. Generating C Code
• Integrate Ruby code in a C application
• Generates C files containing the Ruby code
• A standalone app – without any requirements
• The user doesn't see the source code

20. Performance
• Performance of C compared to MRuby is about
100 : 1
• Probably slower than the latest Ruby

21. But That's OK
• There is a trend in IoT:
• Dumb devices that only provide resources/
services
• Most of the application logic in the cloud
• MRuby fits this use case well despite performance
issues
• Besides it's very young and will improve

22. One Less Issue
• Deploying/updating is a nightmare
• There can be dozens/thousands of embedded systems running your app
• Little power, sometimes constrained battery life
• Testing/debugging on the device takes effort
• You have no control of the environment they are in
• The added trouble of communication with and between devices
• Security...
• You are stuck with C, C++, maybe Java (unless you run on Unix)

23. So, now we have the
MRuby, we just need the
MRuby on Rails

24. My PhD Project
• A platform/framework for deploying apps to embedded devices
• Define some conventions and architecture
• App Store like software ecosystem
• Secure environment for apps
• Open interfaces and communication
• I'm just starting my PhD
• Any feedback is very appreciated